Generally, NTC devices are used for temperature detection of batteries for cellular phones, mobile communication devices, personal computers or for ICs, transistors, crystal oscillators, liquid crystal displays and the like in for electronic devices. An NTC device has a Negative Temperature Coefficient, i.e., presenting decreasing resistance with increasing temperature. Since they are devices which change reversibly, they are used for the purpose of temperature compensation for correcting electric characteristics which are affected by temperature or for the purpose of limiting the surge current of switching power supplies when they are activated.
Conventional NTC compositions are produced by preparing a heat-sensitive composite oxide powder, consisting of expensive rare earth transition elements such as yttrium, lanthanum etc., cobalt and the like, adding an organic binder and other ceramics materials to the powder, blending them again and shaping the mixture into a desired form and sintering it at a high temperature of about 1400 deg. C. for about 2 hours. Then the NTC composition made up of semiconductor ceramics is applied with electrode paste mainly consisting of silver and baked. Further, glass paste is applied to any necessary part and baked to complete an NTC device.
The above-described NTC device employs expensive rare earth transition elements and high temperature baking processes, demanding high cost and resulting in failure to achieve high production yield. Further, the process has lower flexibility, and there are cases where it is not easy for the user to assemble an NTC device into circuit.
In consideration of the problems with the conventional technology, the present invention has been devised to solve the problems, and is to provide an organic NTC composition which does not need expensive material and which can be manufactured at low temperatures, and provide an organic NTC device as well as a production method thereof, which can be easily built into a circuit, achieving high productivity and high working flexibility.